This invention relates generally to the field of envelope feeding apparatus, and more particularly to an apparatus for feeding envelopes to the inserting station of an inserting machine at a high through put rate.
Envelope inserting machines have long been well known and are utilized in a large variety of document processing applications which involve inserting one or more items into an envelope for further handling, such as mailing or other forms of document processing. One particular application where these machines are used involves large high speed multi-function processing apparatus which store a plurality of different types of insert material in individual feeding devices which are added to a basic document that is traveling along an elongate insert material feed path, at the end of which the basic document and the insert materials are formed into a collation which is then inserted into an envelope, all in a continuous operation. Typical examples of applications for these machines are mass mailers such as banks, credit card operations, and telephone and other public utility companies that mail monthly statements or bills to customers, book clubs, catalog mail order companies and other business operations in which certain material is mailed to tens or perhaps hundreds of thousands of customers each month.
These examples involve a typical document handling process in which basic documents, such as monthly invoices, statements, bills, etc., to customers, are computer printed on forms passed through a high speed computer printer in continuous web form, and are then fed through a suitable separating machine which separates the individual invoices from the web, and feeds them into the feed path of a collating machine. The collating machine typically includes a plurality of individual feeding devices which feed any desired number of other documents, such as advertising material, services information brochures, announcements of forthcoming services, sweepstakes entries, etc., into the insert material feed path to add these materials to the basic documents as they travel along the feed path of the collating machine. All of the collated material may be passed through an accumulator or other device that arranges the material in a precisely aligned packet, which is then fed to an inserting machine where the packet is inserted into an envelope which is suitably held at an inserting station. After the packet of documents is inserted into the envelope, it is typically fed through a machine which moistens the envelope flap, turns it 180.degree. and presses it against the back of the envelope to seal it thereto. The now closed and sealed envelope is then typically fed either through a postage metering machine for printing a postage indicia on the envelope or it may be fed directly to a suitable stacking device for further processing.
The problem that arises is that the insert material can be dispensed by the individual feeders and injected into the insert material feed path with the basic document at a much faster rate of speed than that at which individual envelopes can be fed from the envelope storage and feeding device and fed to the location in the inserting machine where the collation of basic document and insert material is inserted into the envelope. The principal reason for this is that in the traditional form of envelope inserting machines, the envelopes are stored in the hopper of a storage and feeding component that is disposed generally above and either to the left or right of the insert location of the inserting apparatus. Thus, there is an envelope feed path for the envelopes between the storage hopper and the insert location that is of some substantial length, in order to provide the room necessary for an envelope flapping device which opens the flaps of the envelopes as they are fed from the storage position to the insert location. In all typical high speed collating and inserting apparatus, the length of this envelope feed path is considerably longer than the typical spacing between successive collations of insert material moving along the insert material feed path because it is not possible to move envelopes from the storage hopper at the same rate as that at which insert material can be moved along the insert material feed path to the insert location. Therefore, the through put capacity of the entire document processing apparatus is limited by the rate at which envelopes can be delivered to the insert location. Further, it is typically not possible to shorten the supplemental feed path because of the space required for the envelope flapping device.
Another factor limiting the rate of envelope feeding is that there is a maximum limit to the linear velocity at which envelopes can be fed along the supplemental feed path from the supply hopper to the insert location, above which jams tend to occur due to the physical nature of envelopes and the fact that the flaps have to be opened, and this maximum limit is typically well below the linear velocity at which insert material can be injected into and fed along the primary feed path. Thus, merely increasing the speed of operation of the envelope storing and separating machine is not a viable solution.
Thus, there is a need for an effective alternative arrangement for feeding envelopes from a storage hopper to the insert location in an envelope inserting machine in which the envelopes can be moved from the storage hopper along the envelope feed path and positioned at the insert location at the same rate at which insert material can be moved along the insert material feed path and positioned at the insert location.